The safety lancet is widely used in various medical units as a medical instrument for taking blood from the human body. The existing lancets can be divided into a puncture lancet and an incision lancet according to the different blood-taking methods. The puncture lancet acts on the blood-taking site by means of acupuncture, mainly used for taking blood from an adult's finger. The incision lancet acts on the blood-taking site by means of blade incision. The incision lancet feels less painful than the acupuncture lancet, and can take enough amount of blood, and therefore it is of a high-level product in various kinds of lancets.
American U.S. Pat. No. 5,133,730 discloses a disposable finger blood-taking device. Such a blood-taking device uses a blade, and realizes the blood-taking purpose by incising the blood-taking site with an incising action. The incising action is performed mainly as below: A button is used to push a first swing arm to swing, which again pushes a second swing arm to swing, which forces a blade on the second swing arm to stretch out of a casing to perform the incising movement; and then the first swing arm pushes the second one to make the blade be retracted into the casing. Being different from a traditional lancet where a sharp needle is pierced into the finger, such a blood-taking device uses a minute blade to incise into the finger, substituting a surgical incising action for the acupuncture action, touching capillaries and small vessels in the finger with the minimum wound and at the most effective depth, reducing damage to the cellular tissues to the utmost, making a patient suffer much less than with the traditional lancet according to tests, barely resulting in discomfort even for the youngest patient. However, such an incision blood-taking mechanism directly makes use of manual push to perform the incising action, and therefore there is a certain requirement on control of the push strength, which brings inconvenience to a user. Therefor, a problem that the present invention emphasizingly studies is how to design a new incision blood-taking mechanism, so as to overcome such a shortcoming.